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Moments after we revealed Britney Spears' Shape Magazine cover, fans started alleging the bikini photo was altered with extreme Photoshopping -- but just how strongly edited was it?

Judging by a side-by-side with a recent real-life swimsuit pic (right, taken in March), not much!

While her cleavage was likely touched up and her skin was smoothed out all around (normal for magazine covers), the curves of her bod are indeed hers.

The 31-year-old credits her fit physique to Nutrisystem, yoga and rehearsals for her upcoming residency in Las Vegas.

"I'm doing 90 minutes of yoga twice a week in addition to a lot of cardio — hour-long sessions three times a week with my trainer," she tells the magazine.

So while Photoshop made her skin glow just a little brighter, that physique came from a lot of hard work and a grueling diet.

See more fit (and some not-so fit) beach bods in the gallery above!

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